Manufacture of dried wood veneer



Aug. 7, 1934.

J. HELFFRICH MANUFACTURE OF DRIED WOOD VENEER Filed March 22. 1932 eachother.

4'0 already according to Patented Aug. A 7, 1934 E NT oFFics 1,969,712MANUFACTURE OF DRIED WOOD VENEER Rheinau,

Mannheim- Germany, assignor to Schiitte-Lanz Holzwerke A. G.,Mannheim-Rheinau, Germany Application March 22, 1932, Serial No.

In Germany February 20, 1931 4 Claims.

This invention relates to a method of producing wood veneer of any widthby feeding the wet veneer band formed to a drying device in a directionrectangularly to the course of the 5 fibers.

Dried veneer is, as a rule, produced by means of a drying devicecomprising a number of pairs of drying plates, the individual dryingplates being mechanically movedtowards, and away from,

The platescorrespond in size to that of the veneer sheets to be dried,and as the dimensions of the plates for structural reasons must be keptdown, the drying devices in common use can handle only veneer sheets ofl5 a limited size. 1

It has further been proposed already to arrange a number of such dryingdevices one behind the other and' to cause the individual systems tocarry out lateral motions in order to convey the veneer sheets'throughthe various systems from one end of the machine to the other. However, amachine of this kind ,is capable only of'conveying the veneer sheets'inthe longitudinal direction of their fibers while the width of the sheetsto be dried by the machine is still dependent on the widthof the dryingv plates. As is knownto those skilled in the art the length of woodveneer covers the'extension in the direction of the fibers and the widthcor- 30. responds to the dimensions measured vertically 'to thedirection ofthe fibers. The length thus refers to the length of the logfrom which the veneer is formed and may amount up to four meters. I

[35. The invention aims 'atiproducing wood veneer of any width bypassing the veneer band, in contrast with the veneer sheet, through thedrying device transversely to the direction of fibers.

Methods of drying which drying is effected by means of a plurality ofsuperposed heating rollers about which the veneer has to be guided. Aslong as the veneer is wet it can be conveniently placed around a roller,but as soon as it 46 begins to dry it becomes brittleand forms crackswhen so applied. It'has been tried to protect thin veneer againstsplitting by passing thin layers of paper through the rollers togetherwith the veneer to 50' has been found that paper strips-glued to. driedveneer cannot prevent or cracking, not to mention the cost involved inapplying and removing the paper. It is impossible, accor to practicaltestsmade, to dry, for instance, in this manner a veneer havveneer bandsare known glue them on to the latter, but it breaking and splitting inga thickness of 3 millimeters without exposing it to fracture orsplitting in the drying device. I

Accbrding to the invention, these drawbacks are overcome by drying theveneer hand between two plane heating plates of known type which aremoved towards and away from each other and between which the veneer ispassed transversely to its direction of fibers. This method permits asimple and clearly arranged construction of the drying device which.iseasy to operate. Furthermore, if the conveying rolls for passingthe'veneer through the heating plates as well as the cutting device aredisposed in the plane of theheating plates, the veneer band can be fedto the cutting device without curvatures or bends and behind the dryingdevice a cooling path or bed may be provided on which the dried, hot-veneer band canbe cooled off so as to permit its piling or further useimmediately after cutting.

One form of apparatus which, according to the invention, can be used {orcarrying out the method is illustrated in the accompanying drawmg.

Referring to the drawing, A is a roll on which the veneer coming offfrom a log is wound. The roll A may of course be dispensed with and theveneer taken directly from the peeling ma.- chine. B is the veneer whichis passed between the two heating plates C, C heated by steam, hot airor electricity. Comparedwith the plates used in the ordinary dryingdevices, the heating plates C,'C"are quite long, up to 5 meters or over,because the longer the plates, the more quickly the veneer can be passedbetween them. In the known types of driers of this class employingalways a large number of superposed heating plates the latter have amaximum length not exceeding ,3 meters.

As described in detail below, the heating plate C is intermittentlyraised and lowered so as to press the wet veneer, the raising of theplate permitting the vapors developed to escape. Behind the plates C, C'a cooling bed D is provided consisting, in the embodiment shown, oi agrate, though it might be constructed in the form of a cooled plate orthe like and be equally eflicient. On the cooling bed I) the hot veneeris cooled down to such a degree that it can be touched by hand; Whilethe veneer lies. on the cooling bed, defective parts may be marked forsubsequent removal by the cutting device F.

' E are conveying rollers actuated by hand or machine and penetratingthe grate or cooling bed D. The top roll E is provided with a handwheel, in the embodiment shown, which can be turned by the operatoraccording to the degree of drying effected which can be ascertained byobserving whether or not steam is developed in a visible manner at theend of the plates C, The nature of the conveying device forms no part ofthe invention. F is a cutting device comprising the lower companionblade and an upper cutter block which can be moved up and down by hand.H is the delivery table whose length may be adapted to the width of theveneer desired.

By ineansof the crank P driven in any'suitable manner the draw bar G'isreciprocated and, by means of an interposed braking cylinder Q, acts onthe piston rod R of the latter which is articulated to the lever Sdisposed at T on the ,frame of the machine and engaging with the rod Xthe lever K rotatably'arranged at V on the machine frame. A draw bar Gconnects the four levers K shown which are thus moved to and fro on, therotation of the crank P. To the other arm of the levers k arearticulated the members I at W and secured with their upper ends to theplate C which is thus raised andlowered when the crank P is turned, thecontact between the plate C and the veneer being timed and controlled bythe adjustment of the braking cylinder Q. I

One of the essential features of the method is that the veneer iscontinuously passed between the plates C according to the degree ofdrying ascertained by observation.

L indicatesthe lower frame portion, M are transverse braces, N arevertical supports and 0 is the upper frame portion.

The device functions as follows:

The veneer band B coming from a roll or directly from the peelingmachine is passed between the heating plates C, C by hand or by means ofsuitable devices, not shown, when the plates are in opened position, anddrawn between the rolls E which do the further feeding of the veneer B.gradually according to the opening and closing of the plates. The rollsE are, as shown, driven by hand, or, not shown, mechanically, i. e. bythe member G, and-their speed is regulated so that the portion of theband B coming out of the drier has attained the desired degree ofdryness. The band B then passes on tothe coolerD andthe cutterl k-Theveneer sheetscanbepiledanduseddirectlyafterbcing cut.

I claim: 1. A device for producing dried veneer, cunprising a peelingdevice separating an endless band of wood transversely to the course atits fibers from a trunk, intermittently moved transporting means forcarrying the hand away, heatable plates on both sides of said band,driv- I ing means for moving saidheatable plates so as to cause saidplates to press the band when stationary between them for apredetermined time, and cutting means for separating the band intoindividual dried veneer plates. N

2. A device for producing driedveneer, comprising means for introducingan endless hand of wood transversely to the course of its fibers,intermittently moved transporting means for carrying the band away,heatable plates on both sides of the band, driving means for moving saidheatable plates so as to cause said plates to press the band whenstationary between them tor a predetermined time, and cutting meansdorseparating the band into individual dried veneer 1U plates. 3. A devicefor producing dried. veneer, comprising means for introducing an endlessband of wood transversely to the course of its fibers, intermittentlymoved transporting means for con-- veying the band, heatable platesdisposed on both sides of the band of wood and actlm as ventilatingdrier therefor, means for moving said heatable plates so as to came saidplates to press the band when stationary between them for apredetermined'time, and cutting means for separating the band into.individual dried plates.

4. A device for producing dried veneer, eanprising means for introducingan band oi. wood transversely to the course of its fibers,intermittently moved transporting means for con-' veying the band,heatable plates on both sides of the band, said' plates being plane anddisposed partly above and below the band to be m dried, driving meansfor moving said heritable plates so as to cause said plates to press thehand when stationary between them for a predetermined time, and cuttingmeans'for separating the band into individual dried veneer sheets.

\ JOSEF

